Tasmania in 2010: another warm year

2010 was warmer than usual across Tasmania, especially by day
and
especially from January to July. Several heavy rain events gave the
north a wetter than usual year, but the south was drier than usual
overall. Significant weather events included huge waves and snow in
September.

Warm overall

2010 was a warm year across Tasmania, with higher than normal
temperatures in most months. Mean
daytime maximum and overnight minimum temperatures were both around
half a degree
warmer than the long-term average, and Hobart and Eddystone Point had their
highest mean daily maximum temperature
on record.

January had several hot days, including 40.7 °C at
Ouse on 11 January, one of
only four days when temperatures this high have ever been measured
in Tasmania. More hot weather included 9 January in the
northwest when Devonport
reached 33.2 °C,
its hottest
temperature on record by several degrees. The warm
conditions continued from February to April, with Hobart having a
record long run of mild days and a handful of sites having their warmest
night (highest daily minimum temperature) on record.
March and April were particularly warm. There
was a cool period at the end of April and in mid-May, but milder than
usual conditions returned in June and July. The seven months from
January to July gave
the warmest such period on record for Tasmania. Cooler than normal
temperatures became more common from August, especially in September and December,
but it was still a warm year overall.

Daytime
temperatures were more anomalous than overnight temperatures: while
days were warmer than usual in nearly every month of the year, cold
nights became common from May. The coldest night was -10.2 °C
at
Liawenee on 22 May. Unusually, the coldest days for the year occurred
in September, with Mount Wellington reaching only
-2.2 °C on
the 28th and -2.1 °C
on the 29th. On these days, snow settled to around 200 metres in the
south. The first
morning
of the year was the warmest, with a very mild minimum temperature of
22.0 °C at
Friendly Beaches.

Unusually wet in the north, but a dry year in the south

Overall, 2010 was
wetter than usual in the north but drier than usual in the south.
Several months between August and December were much wetter than usual,
but failed to fully compensate for the record dry conditions
that developed in the southeast during January to July. The driest
sites
were in the southeast, with just 409
mm falling at
Hobart Airport and 420
mm at Campania.
Parts of the Derwent Valley were also very dry, with Ouse having only
418 mm. In contrast, Mount Read was the wettest site with a total
of 3955 mm. Most of the state was drier than in 2009,
but a few sites
in the north were their wettest for quite a few years, and Launceston
had its wettest year
since records began at the current site in 1980.
A few sites had their highest
daily
rainfall on record during one of the heavy rain events
through
the year.

Little rain fell in January, with several sites having their
lowest
January rainfall on record. There were average to above-average falls
in the north between February and April, but drier than usual
conditions persisted in the south. May was again drier than usual
in most areas, except for a small part of the east coast that had
record heavy falls on 28-29 May. Gray received 203 mm in one
day, the highest daily total for the year. After record low
rainfall in the southeast during June and July, several sites,
including Hobart, had their driest January-to-July on record.

Weather
patterns changed in August, and statewide rain became more common. The
11th
of August was especially wet,
with daily totals reaching 199 mm on Mount Wellington (Tasmania's
second-wettest August day on record) and 182 mm at
Gray. Major flooding developed in the South Esk River with moderate
flooding in several other rivers. September, November
and December were also wetter than usual over large areas of the
state.

A very warm
year for Hobart

The first seven months were
record warm and record dry for Hobart, but there was a prevalence
of cooler and wetter weather after that. Averaged over the whole year,
the
mean daily maximum temperature for Hobart was a record
high 18.2
°C,
1.3 °C above the long-term average and fully 0.2 °C
clear of
the
previous record from 1988. The
mean overnight minimum temperature was
9.0 °C, 0.7 °C above the long-term average.
Taken together
these gave
Hobart a mean annual temperature of 13.6 °C,
just below the record 13.7 °C recorded in 1988.

Rainfall was very low in Hobart until August, but some wetter weather
during spring meant the total for the year was 524
mm, below the
long-term average of 616 mm. This is well below the 2009 total of 865
mm
but well above the record dry 347 mm that occurred in 2006.

Some significant events in Tasmania in 2010

Huge
waves:
Near-record waves around Tasmania were generated by a deep low pressure
system on 16 September. At the waverider buoy off the west coast,
waves averaged over 8 metres for most of the day and peaked at
18.4 metres, approaching the record wave of 19.8 metres measured by a
similar buoy operated by CSIRO in July 1985. Both Maatsuyker Island and
Cape Bruny reported swells of at least 10 metres on this day.

Snow:
Most of the significant snow for the year fell in spring with falls to
low levels on 15-16 September, 27-29 September and 15-16 October. There
were also several snow days in August, but prior to that it was a mild
autumn and winter with little snow except on the highest
peaks.

Tsunami:
A tsunami was generated by an earthquake off the coast of Central Chile
on 27 February. After moving through the Pacific Ocean, it reached the
east
coast of Tasmania the next morning and caused tidal fluctuations of 17
cm at Maria Island and Southport.

Strong
winds:
Usually Tasmania experiences strong winds in autumn, winter and spring.
This year, however, it was calmer than usual during these seasons. The
strongest winds occurred on 10 December, with gusts reaching 157 km/h
at
Maatsuyker Island.

Notes

A Annual Climate Summary is prepared to list the main features
of
the weather in Tasmania using the most timely and accurate information
available on the date of publication; it will generally not
be updated. Later information, including data that has had greater
opportunity for quality control, will be presented in the Monthly Weather Review,
usually published in the fourth week of the month.

This statement has been prepared based on information available at 9 am on Wednesday 5 January 2011.
Some checks have been made on the data, but it is possible that results
will change
as new information becomes available.

Averages are long-term means based on observations
from all available years of record, which vary widely from site to
site.
They are not shown for sites with less than 10 years of record, as they
cannot then be calculated reliably.
The median
is sometimes more representative than the
mean
of long-term average rain.

The Rank indicates how rainfall this time compares
with the climate record for the site,
based on the decile
ranking (very low rainfall is in decile 1,
low in decile 2 or 3,
average in decile 4 to 7, high
in decile 8 or 9 and very high is in decile 10).
The Fraction of average shows how much rain has
fallen this time as a
percentage
of the long-term mean.